1. Field of the Invention
The present invention relates to an improved electric switch and to an improved device using the improved switch. More specifically, the present invention constitutes an improvement of the invention claimed in commonly-assigned U.S. patent application Ser. No. 972,650, filed Dec. 21, 1978 (now abandoned) in the name of Otto Meister Ser. No. 21,646, filed Mar. 19, 1979 in the name of Otto Meister, which issued as U.S. Pat. No. 4,342,978 on Aug. 3, 1982.
The '650 application relates to a circuit-protection device which includes a first current path having a high continuous current-carrying rating. A pair of normally electrically interconnected contacts are included in the first path. The contacts are relatively movable apart along a fixed line of direction. When the contacts move apart, the electrical interconnection therebetween is broken to open the first path. When the contacts are electrically interconnected, at least one of them defines a portion of an enclosed chamber. An ignitable device, such as a power cartridge, is included in the chamber for pressurizing it upon ignition thereof to rapidly drive the contacts apart. A second current path is in electrical shunt with the contacts and physically surrounds the first path. The second path may include a fuse or a fusible element which may be either current limiting or non-current limiting. The first path normally shunts away from the fusible element the majority of the current passing through the device. Only when the contacts move apart is current commutated to the fuse which then interrupts such current. Preferably, the power cartridge is ignited to move the contacts apart in response to the occurrence of a fault current or other over-current in a circuit in which the device is connected. As more fully explained in the '650 application, in this way current-limiting fuses, which may have high fault current interrupting ratings but which can carry only low continuous currents may be used to protect circuits having high continuous currents because the first path (including the contacts), and not the fuse, normally carries the majority of the current in the circuit.